Operator assist device for sewing machines or the like



Nov. 21, 1967 s. M. MARINO 3,353,511

OPERATOR ASSIST DEVICE FOR SEWING MACHINES OR THE LIKE Filed Feb. '7, 1966 z 55 a K v I:

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A f u 23 INVENTOR. Salvafore M. Marina ATTORNEY BEST AVAILABLE COPY 3,353,511 Patented Nov. 21, 1967 3,353,511 GPERATOR ASSIST DEVICE FOR SEWING MACHINES GR THE LIKE Salvatore M. Marino, East Brunswick, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Feb. 7, 1966, Ser. No. 525,580 3 Claims. (Cl. 112-237) This invention relates to devices for minimizing the efi'ort required to be expended by a sewing machine operator incident to the manipulation of controls, appurtenances, or the like associated with the sewing machine.

Power control units are known in the prior art which upon a signal as from the machine operator assume completely the operation of a control device, appurtenance, or the like. A disadvantage of these known units is that the operator loses the feel of the operation and cannot influence the speed or degree of occurrence thereof.

It is an object of this invention to provide an operator assist device which automatically provides a high percentage of the effort required to perform the necessary control of appurtenance manipulation but leaves to the operator a small but noticeable increment so that the operator retains full control over the rate and degree of performance.

With the above and additional objects and advantages in view, as will hereinafter appear, this invention will be described with reference to drawings in which the invention is applied to a presser foot lifting mechanism of a sewing machine and in which:

FIG. 1 represents a side elevational view of a sewing machine partly in cross section having this invention applied thereto, and

FIG. 2 is an enlarged vertical cross sectional view of the operator influenced valve device of FIG. 1.

In the drawings 11 indicates the frame of a conventional sewing machine which is supported upon or fitted with a depending lubricant collecting pan 12. In addition to various sewing instrumentalities (not shown), the sewing machine frame carries a presser foot 13 which is secured to the lower end of a presser bar 14 endwise slidably journaled in the sewing machine frame. The presser bar is biased downwardly by a coil spring 15 of which the pressure may be adjusted by a regulating screw 16 threaded in the top of the frame.

The presser foot serves, as is well known in the art, to hold work fabrics relatively to the sewing instrumentalities and to maintain the work fabrics relatively to work feeding mechanism of the sewing machine. It is a requirement of sewing machine operation that the operator be able to raise and lower the presser foot in opposition to the spring 15 in a variety of different ways for a variety of different reasons. To introduce and remove work fabrics from the stitching instrumentalities it may be desirable to raise the presser foot an appreciable distance. To facilitate turning the work fabric at a sharp angle during the sewing process it may be desirable to raise the presser foot only slightly. To rearrange a hem fold or pleat in the work fabric it may be desirable to raise the presser foot to an intermediate position. Similarly, while instances may occur when the rate of descent of the presser foot is of no concern, at other times, as when particular care must be taken not to disarrange Work fabric folds or the like therebeneath, it is desirable that the presser foot be lowered slowly into engagement with the work fabric.

For raising and lowering the presser foot 13, the presser bar 14 is operatively connected to one extremity 20 of a lever 21 fulcrumed on a shouldered screw 22 on the sewing machine frame. Underlying the lever extremity 20 is an operator influenced cam lever 23 which is fulcrumed on the screw 24 and formed with cam lobes 25 which act to turn the lever 21 to raise and lower the presser foot when the operator influenced cam lever 23 is turned.

In order that the presser foot may be raised and lowered by a treadle or knee shift device, the opposite extremity 26 of the lever 21 is apertured, as at 27, and accommodates a pull rod 28 on which stop nuts 29 are threaded above the lever extremity 26. The pull rod extends downwardly into the machine frame and is rigidly secured or otherwise fastened to one extremity 30 of a lever 31 which is fulcrumed, as at 32, on a bracket 33 depending beneath the machine frame 11. The opposite extremity 34 of the lever 31 is flattened to provide an abutment for a push rod 35 which is endwise slidable in a bushing 36 formed in the lubricant collecting pan 12 beneath the machine frame.

lournalled in a bracket 37 beneath the lubricant collecting pan 12 is a rock shaft 38 to which is secured a rock arm 39 underlying the push rod 35 and a depending rock arm 40 on which an operator influenced knee pad 41 is carried.

The presser foot raising and lowering mechanisms thus far described are conventional, and in such conventional devices the knee .pad 41 is ordinarily secured rigidly to the depending rock arm 40 usually with provision for selectively positioning the knee pad along the rock arm to suit the individual machine operator.

In the present invention, however, there is interposed between the knee pad 41 and the depending rock arm 40 a special mounting block which supports a fluid pressure valve 51 and to which block 50 the knee pad is articulated in a unique fashion so as to influence the fluid pressure valve 51 incident to shifting of the rock arm 40.

Fluid under pressure is directed to the valve 51 by a conduit 52 from a source of supply which is indicated in the drawing as a shut-off valve and pressure gauge 53. A conduit 54 leading from the valve 51 is directed to a cylinder 55 carried on a bracket 56 secured by screws 57 to the sewing machine frame 11. A piston rod 58 extending from the cylinder 55 passes through an aperture 59 in the extremity 26 of the lever 21 and a stop nut 60 on the piston rod provides an abutment operatively engaging the lever 21.

Referring to FIG. 2, the mounting block 50 is formed with a bore accommodating the rock arm 40 and the block is threaded for a fastening screw 71 by which the block 50 may be secured in selected position along the rock arm. A slot 72 formed in the block 50 generally parallel to the bore 70 accommodates the fluid pressure valve 51 which is secured in the slot by screws 73.

The fluid pressure valve 51 is preferably a conventional type including threaded hose fittings 74, 75 one at each side for the conduits 52 and 54, respectively, and a spring loaded operating plunger 76 which when depressed opens a passageway between the conduits 52 and 54 and which when released closes the passageway between the conduits. It is also preferable that the valve 51 be of the type having an exhaust outlet 77 to which the conduit 54 is opened when the plunger is released. In this way the pressure applied to the cylinder 55 will be relieved when the valve 51 separates the source of fluid pressure supply from the cylinder.

The knee pad 41 illustrated in the drawing is formed of resilient material and provided with a recessed pocket 80 into which a fastening plate 81 may be forced. The fastening plate 81 is formed with a plurality of spaced apertures 82 each loosely accommodating the elongate shouldered portion 83 of one of a plurality of shouldered screws 85 threaded into the mounting block 50. This support for the plate 81 provides for depression of the valve plunger upon canting of the plate 81 in any direction so that the device will operate satisfactorily regardless of the position of an operators knee against the pad 41. A coil spring '85 is constrained in a transverse bore 36 in the mounting block and is compressed by an adjusting screw 87 threaded into the bore so as to engage and bias the fastening plate 81 outwardly against the headset the shouldered screws 84.

When the sewing machine operator presses against the knee pad to raise the presser foot, the initial movement of the knee pad will cause the fastening plate 81 to partake of a lost motion along the shouldered screws 34 against the action of the coil spring 85. Since the valve plunger 76 abuts the fastening plate 81, this lost motion of the knee pad will open the valve 51 to connect the source of fiuid pressure 53 with the cylinder 55 before the mechanical connections to the presser lifter are actuated. Further movement of the knee pad by the operator, however, will shift the mechanical connections to the presser lifter in the conventional fashion while maintaining the valve 51 open.

The pressure delivered to the cylinder 55 is preferably regulated by the valve 53 to that amount which will give rise to a force upon the piston rod 53 which is less than that required to overcome the force of the presser spring 15. As a result, the fluid pressure system will be insuflicient to raise the presser foot but it will diminish the effort required of the operator to effect shift of the presser device.

The operator with this arrangement retains full control over the height to which the presser foot is raised and of the rate at which the presser foot raises and lowers. The operator, however, accomplishes such controlled manipulation of the presser foot with application of only a small fraction of the effort customarily required.

The system illustrated in the drawings is particularly adapted to pneumatic operation in which case the exhaust outlet 77 simply communicates with the atmosphere by way of a clearance hole 90 through the block 50. An hydraulic system may be used with equal effectiveness, but in such case a return conduit from the outlet 77 would be advisable.

The proportion of the force necessary to oppose the presser spring 15 which is provided by the cylinder 55 may 'be varied by regulating the pressure delivered by the valve 53 into the system. In practice, successful operation has been experienced by regulating the pressure to provide approximately 80 percent of the total force required to raise the presser foot.

BEST AVAILABLE COPY It is pointed out that the frictional resistance which is present in the mechanism for raising and lowering the presser foot opposes and adds to the force required to overcome the spring 15 when the presser foot is being raised while these frictional forces diminish the force necessary to counteract the effect of the spring 15 when the presser foot is being lowered. In order, therefore, to retain operator control over both the raising and the lowering of the presser foot, the fluid pressure should be adjusted to that value which will provide a force applied by the piston rod 58 which is slightly less than that required to sustain the presser foot at any given elevation as it is being lowered.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A sewing machine having an appurtenance shiftably supported thereon, an operator influenced linkage carried by said sewing machine and operatively connected to said appurtenance, said linkage including provision for a predetermined increment of lost motion incident to the shifting of said appurtenance, valve means carried by said sewing machine and responsive to said lost motion in said linkage, a fluid pressure operated drive member carried by said sewing machine and operatively connected to said appurtenance, a source of fluid under a regulatable pressure, and conduit means interconnecting said drive memher and said source with said valve means.

2. A sewing machine as set forth in claim 1 in which a support for an operator influenced element is carried on said linkage, in which said lost motion is provided by a means on said support for constraining said operator influenced element for said predetermined increment of lost motion relatively to said linkage, and in which said valve means is carried on said linkage and is responsive to said lost motion of said operator influenced element.

3. A sewing machine as set forth in claim 1 in which said source of fluid under pressure is regulated so as to influence said drive member to exert only a fraction of the effort required to shift said appurtenance.

References Cited UNITED STATES PATENTS 2,067,038 1/1937 Andres 112-237 2,250,992 7/1941 Kaier l12237 2,664,841 1/1954 Hale et al. 112237 PATRICK D. LAWSON, Primary Examiner. 

1. A SEWING MACHINE HAVING AN APPURTENANCE SHIFTABLY SUPPORTED THEREON, AN OPERATOR INFLUENCED LINKAGE CARRIED BY SAID SEWING MACHINE AND OPERATIVELY CONNECTED TO SAID APPURTENANCE, SAID LINKAGE INCLUDING PROVISION FOR A PREDETERMINED INCREMENT OF LOST MOTION INCIDENT TO THE SHIFTING OF SAID APPURTENANCE, VALVE MEANS CARRIED BY SAID SEWING MACHINE AND RESPONSIVE TO SAID LOST MOTION IN SAID LINKAGE, A FLUID PRESSURE OPERATED DRIVE MEMBER CARRIED 